Wouldn't it still be other people getting a say in how your money is spent, not you? If you're not sending anyone to school, you're still not the one making the decision. It just happens to be parents, not the government. It's the consumer making the choice, and I can see why a lot people would prefer that idea, even if I personally don't.
School vouchers seem to me like you're dooming a vast majority of underperforming schools to a
slow faster death, while the few best schools prosper even more. That would be fine and wonderful if all the kids in the country could go to those few best schools, but that's not possible. I think it's more likely that a vast majority of kids would be stuck in the ones hemorrhaging funds while vouchers walk out the door.
There are problems with the education system, obviously, but I would rather try and see them fixed than just throw our collective hands up and say "Screw it, here's some money, go where you want." That amounts to giving up on the majority of school-going kids. Not everybody can afford to drive their children to a more distant school, after all, and you can only expect someone to walk so far. So you aren't solving any problems. It's a cop-out.